The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of integrated circuit evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased.
As a part of the semiconductor fabrication, conductive elements may be formed to provide electrical interconnections for the various components for an IC. Typically, these conductive elements are formed by etching trenches+via or openings in various layers and filling these trenches+via with a conductive material. However, as semiconductor fabrication technology nodes continue to evolve, the critical dimension is becoming so small that filling trench+via with the conductive material may not be easy. Often times, issues such as voids or overhang may arise during the filling of the trenches+via. These issues may degrade the performance of the semiconductor device and may even lead to device failures.
Therefore, while conventional filling techniques have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.